﻿using System;

class TrapezoidArea
{
    static void Main(string[] args)
    {
        Console.WriteLine("Side a:");
        double SideA = double.Parse(Console.ReadLine());
        Console.WriteLine("Side b:");
        double SideB = double.Parse(Console.ReadLine());
        Console.WriteLine("Height:");
        double HeightH = double.Parse(Console.ReadLine());
        Console.WriteLine("The area of the trapezoid is {0}",((SideA + SideB)/2)*HeightH);
    }
}

